#include <iostream>
#include <cmath>
using namespace std;

float sq(float n){
	return n*n;
}
double dis (float x1,float y1,float x2,float y2){
	return sqrt(sq(x1-x2)+sq(y1-y2));
}
int main(){
	float x1,x2,x3,y1,y2,y3;
	double ans = 0.0;
    scanf("%f %f\n%f %f\n%f %f",&x1,&y1,&x2,&y2,&x3,&y3);
    ans += dis(x1,y1,x2,y2);
    ans += dis(x2,y2,x3,y3);
    ans += dis(x1,y1,x3,y3);
	printf("%.2f",ans);
}
